New Bone Grown from Monkey's Own Skin Cells

The five most athletic primates are named in the world's most comprehensive guide on primates, "Handbook of the Mammals of the World" (Lynx Edicions, 2013), released this week.
The number one athletic monkey, according to the guide, is the Patas monkey. Editors Russell Mittermeier, Anthony Rylands and Don Wilson write that these "are the fastest primates, relying on their speed to escape from predators." Their running speed can reach up to 34 miles per hour.

Alex Roberts, Wikimedia Commons

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The indri is the largest living lemur. "Its hind limbs propel it through the trees in leaps up to 30 feet," according to Mittermeier, Rylands and Wilson. The leaps allow the lemur to efficiently travel high in the forest canopy, where it searches for food such as tender leaves, seeds, fruits and flowers. The leaps also often allow it to jump out of the way of predators, like hawks that can go after young indri.

Russell Mittermeier, Conservation International

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The weight-lifting champ of the group is the bearded capuchin. These primates "can lift heavy rocks and smash them down to crack open palm fruits," according to the editors.
The bearded capuchin, also known as the black-striped capuchin, was the first non-ape documented to use tools in the wild. Over the years, the monkeys have evolved strong back and leg muscles that enable them to walk on their hind legs while carrying stones.

Russell Mittermeier, Conservation International

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"Long-tailed macaques are skilled swimmers and can catch fish with their own hands," Mittermeier, Rylands and Wilson share. These primates sleep in trees alongside rivers, taking time to select their roosting sites. When a predator approaches, they frequently jump into the water and swim out of harm's way.

Muhammad Mahdi Karim, Wikimedia Commons

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"Gibbons are masterful acrobats, swinging hand over hand with uninterrupted leaps through the forest canopy," according to the editors. Their relatively tiny size -- about 20 inches long -- makes them even faster as they glide through the air. Their swinging lifestyle allows them to exploit fruits and other foods that larger bodied arboreal animals cannot reach.

The US study is the first time such a development has been shown in an animal that is similar to humans.

Professor Martin Pera, program leader of the ARC Stem Cells Australia, says the work, published today in Cell Reports, is "another step towards the development of safe stem cell therapies for human disease".

The study uses induced pluripotent stem cells (iPSC), which are derived from adult skin cells and can be reprogrammed to work as other cells.

Pera says pluripotent stem cells can be used to make any type of healthy human tissue and therefore have great potential for treatment of disease.

However, he adds, knowledge of whether stem cell therapies will be safe and effective in a clinical setting is limited.

Senior author of the new study, Dr Cynthia Dunbar, at the National Heart, Lung, and Blood Institute in the US, says their findings go some way in addressing these concerns and sidesteps ethical issues surrounding the use of embryonic stem cells.

Previous work in this field has relied on scientists giving human iPSC products to immunodeficient mice, she says.

"But because of the species differences, the cells do not behave normally in mice, and the lack of the immune system means that issues of immune rejection or inflammation cannot be studied," says Dunbar.

Because monkeys are the closest model species to humans, with similar organ and tissue structure and immunity, testing monkey iPSCs in monkeys should be indicative of the safety and efficacy of the process in humans, Dunbar says.

For the study, skin cells were taken from rhesus macaques to form stem cells (iPSCs), which were then turned into bone-forming cells.

Dunbar says those "bone" cells were then implanted into the monkeys on ceramic particles that were already in use by reconstructive surgeons attempting to fill in or rebuild bone.

The implants were retrieved at eight, 12 and 16 weeks with bone shown to be forming as early as eight weeks, the authors report.

Dunbar says unlike in studies involving mice injected with iPSCs the risk of tumours developing in the rhesus monkeys appeared to be low.

"The teratomas (tumours) only formed following injection of very high doses of undifferentiated iPSCs into animals, and even then the teratomas grew very slowly," she says.

Pera says because the approach uses a technique to produce stem cells that can be customised to individual patients, it avoids the potential for immune rejection of the graft.

He describes the results from the US study as "encouraging in terms of the safety of pluripotent stem cell therapy".

"However, the study is small, it relates to the safety of only one type of specialised cell, and does not show directly that the bone grafts would heal or repair fractures," he adds.